Astroglial Hmgb1 regulates postnatal astrocyte morphogenesis and cerebrovascular maturation

Astrocytes are intimately linked with brain blood vessels, an essential relationship for neuronal function. However, astroglial factors driving these physical and functional associations during postnatal brain development have yet to be identified. By characterizing structural and transcriptional changes in mouse cortical astrocytes during the first two postnatal weeks, we find that high-mobility group box 1 (Hmgb1), normally upregulated with injury and involved in adult cerebrovascular repair, is highly expressed in astrocytes at birth and then decreases rapidly. Astrocyte-selective ablation of Hmgb1 at birth affects astrocyte morphology and endfoot placement, alters distribution of endfoot proteins connexin43 and aquaporin-4, induces transcriptional changes in astrocytes related to cytoskeleton remodeling, and profoundly disrupts endothelial ultrastructure. While lack of astroglial Hmgb1 does not affect the blood-brain barrier or angiogenesis postnatally, it impairs neurovascular coupling and behavior in adult mice. These findings identify astroglial Hmgb1 as an important player in postnatal gliovascular maturation.

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Baptiste Lacoste Jun 26, 2023 As As we we have described in in the Method section, LabChart 8 software (ADInstruments, CO) was used for laser Doppler flowmetry and electrocorticography data collection. ZenPro 2.6 software (Carl-Zeiss-Strasse, Germany) was used with Zeiss Axio Imager M2 M2 microscope equipped with a digital camera (Axiocam 506 mono) and the Zeiss ApoTome.2 module was used to to collect immunohistochemistry and immunocytochemistry images. JEOL JEM-1400plus transmission electron microscope equipped with a Gatan digital camera was used to to collect capillary imaging; Software used TEM center 1.7 for JEM-1400Flash and DigitalMicrograph 3.5 (Tokyo, Japan). Nanostring data collected by by NanoString GeoMx® Digital Spatial Profiler 3.0.0.111 (GeoMx DSP) (Seattle, WA). Behaviour was recorded and analyzed using EthoVision 14 14 XT XT software program. Westen blot imaging collected using Image Lab software V3.5. RNA-Seq library sequencing was performed using FASTX-toolkit (http://hannonlab.cshl.edu/fastx_toolkit/). ImageJ2 version: 2.3.0/1.53f (Bethesda, Maryland, USA) was used as as well for analysis of of immunofluorescent images. Nanostring data analyzed by by Nanostring GeoMx DSP Data Analysis Suite (v2.4) [SEV-00090-05](Seattle, WA). Behaviour was recorded and analyzed using EthoVision software program 14 14 XT. LabChart 8 software (ADInstruments, CO) was used for laser Doppler flowmetry and electrocorticography data analysis. Computational morphometric analysis of of 3D 3D vascular images was completed using a Gaussian smoothing filter as as well as as a Palágyi-Kuba thinning algorithm (PMID:25155955) as as described in in the methods section. Automated analysis of of immunofluorescence images performed with the use of of Adam optimization algorithm and Palágyi-Kuba thinning algorithm. Analysis of of neuronal density from 2D 2D neuronal images was completed using the Laplacian of of Gaussian (LoG) filter as as described in in the methods section. Graphpad Prism 9.0 & 9.3 software (GraphPad Software, CA). Western blot images analyzed using Image Lab software V3,5. RNA-Seq alignment of of the reads, and normalization as as well as as identification of of differentially expressed genes were performed using STAR (v2.7.9a) and DESeq2, respectively. nature portfolio | reporting summary

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